Hi Iain,
books been finished for a while - just trying to get it published at a reasonable price is my biggest hurdle.
Ok, to the guitar at hand . . .
Up until late 1982, the '5' at he end of the number indicated a Natural finish and nothing else. The 6 or so Custom colours that were offered along with the stock 5 colours were all the same price. With the advent of the Goldstar that changed. Natural and Custom colours were 5,000 yen extra.
To have the stamp at the end of the fingerboard means the serial number is before 0009600 which makes it 1980 or earlier.
sorry guys, I cant seem to find the pics . . .
Peter Mac